Biology, 09.12.2020 14:00 chrisannedegraff

Difference between annual and perennial plants any two please

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Annual plants live for one growing season and then die, while perennials regrow every spring. ... The difference, according to plant geneticist Siegbert Melzer and his team, comes down to two critical flower-inducing genes that, when turned off, can make an annual plant regrow every year.

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americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.

Answer from: Quest

Mantle convection is the slow creepingmotion of earth's solid silicate mantle caused by convection currents carrying heat from the interior to the planet's surface.[1][2] the earth's surface lithosphere, which rides atop the asthenosphere (the two components of the upper mantle), is divided into a number of plates that are continuously being created and consumed at their opposite plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with seafloor spreading. this hot added material cools down by conduction and convection of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of subduction usually at an ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4] while in other regions, this material is impeded from sinking further, possibly due to a phase transition from spinel to silicate perovskiteand magnesiowustite, an endothermic reaction.[5]the subducted oceanic crust triggers volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6] and mantle plumes.[7]it is because the mantle can convect that the tectonic plates are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the hadean period, resulting in gravitational sorting of heavier molten iron, and nickel elements and sulphides in the core, and lighter silicate minerals in the mantle.